So i have been trying to overclock my i5 8600k and have been having problems running RealBench for more than 6-8 minutes, so i reverted my bios to stock settings (not even XMP) and ran RealBench and it detected instabilities.
Have i just out of luck in the cpu lottery?
i assume this is not normal, and was wondering if anyone else had this issue, air there is a way to configure a stable overclock even though this is the case?

thanks all for looking at this, and I look forward to hearing any helpful tips you may have

Titan

Start with the basics. DO you have the MOST recent BIOS version installed? If you don't know, check, and update as necessary. It would be advisable to first reset the BIOS to factory defaults by doing a hard reset of the CMOS, BEFORE updating, or if you are already on the latest BIOS version, it would still be a good idea given the nature of your problems.

Power off the unit, switch the PSU off and unplug the PSU cord from either the wall or the power supply.

Remove the motherboard CMOS battery for five minutes. During that five minutes, press the power button on the case for 30 seconds. After the five minutes is up, reinstall the CMOS battery making sure to insert it with the correct side up just as it came out.

Now, plug the power supply cable back in, switch the PSU back on and power up the system. It should display the POST screen and the options to enter CMOS/BIOS setup. Enter the bios setup program and reconfigure the boot settings for either the Windows boot manager or for legacy systems, the drive your OS is installed on if necessary.

Save settings and exit. If the system will POST and boot then you can move forward from there including going back into the bios and configuring any other custom settings you may need to configure such as Memory XMP profile settings, custom fan profile settings or other specific settings you may have previously had configured that were wiped out by resetting the CMOS.

I followed your advice downloaded and flashed the latest BIOS (F9b) and left the whole thing stock and ran RealBench, didn't even make it 1 minute before it detected instability, any thoughts on what I should be looking at to see if there are hardware faults?
Thanks

Also, I'd try removing and reinstalling your memory, making sure that they are installed in ONLY the A2 and B2 slots, which are the second and fourth slots over from the CPU socket, if you have only two memory modules installed. If you have four, then it doesn't matter where they are installed so long as they all came together in a kit.

What are your full system specs?

Please also download CPU-Z, install it, run it and take screenshots of the Memory and the SPD tabs. On the SPD tab you will need to select the slots (One at a time, taking screenshots of each set of data) that the memory modules are installed in from the drop down menu at the top left of the tab for the data on that module to show up.

Post screenshots here by uploading the images to imgur or tinypic, or another hosting service, and then clicking on the picture icon on the toolbar above each post and inserting the "direct layouts" URL there.

Titan

Remove two memory modules, leaving only two sticks in slots A2 and B2 (Second and fourth over from the CPU). Reset the BIOS using the CMOS battery method I outlined earlier AFTER you remove the two other memory modules. Then test those sticks using Memtest86.

Memtest86

Go to the Passmark software website and download the USB Memtest86 free version. You can do the optical disk version too if for some reason you cannot use a bootable USB flash drive.

Create bootable media using the downloaded Memtest86 (NOT Memtest86+, that is a different, older version and is outdated). Once you have done that, go into your BIOS and configure the system to boot to the USB drive that contains the Memtest86 USB media or the optical drive if using that option.

2. Right click on the downloaded file and select the "Extract to Here" option. This places the USB image and imaging tool into the current folder.

3. Run the included imageUSB tool, it should already have the image file selected and you just need to choose which connected USB drive to turn into a bootable drive. Note that this will erase all data on the drive.

No memory should ever fail to pass Memtest86 when it is at the default configuration that the system sets it at when you start out or do a clear CMOS by removing the CMOS battery for five minutes.

Best method for testing memory is to first run four passes of Memtest86, all 11 tests, WITH the memory at the default configuration. This should be done BEFORE setting the memory to the XMP profile settings. The paid version has 13 tests but the free version only has tests 1-10 and test 13. So run full passes of all 11 tests. Be sure to download the latest version of Memtest86. Memtest86+ has not been updated in MANY years. It is NO-WISE as good as regular Memtest86 from Passmark software.

If there are ANY errors, at all, then the memory configuration is not stable. Bumping the DRAM voltage up slightly may resolve that OR you may need to make adjustments to the primary timings. There are very few secondary or tertiary timings that should be altered. I can tell you about those if you are trying to tighten your memory timings.

If you cannot pass Memtest86 with the memory at the XMP configuration settings then I would recommend restoring the memory to the default JEDEC SPD of 1333/2133mhz (Depending on your platform and memory type) with everything left on the auto/default configuration and running Memtest86 over again. If it completes the four full passes without error you can try again with the XMP settings but first try bumping the DRAM voltage up once again by whatever small increment the motherboard will allow you to increase it by. If it passes, great, move on to the Prime95 testing.

If it still fails, try once again bumping the voltage if you are still within the maximum allowable voltage for your memory type and test again. If it still fails, you are likely going to need more advanced help with configuring your primary timings and should return the memory to the default configuration until you can sort it out.

If the memory will not pass Memtest86 for four passes when it IS at the stock default non-XMP configuration, even after a minor bump in voltage, then there is likely something physically wrong with one or more of the memory modules and I'd recommend running Memtest on each individual module, separately, to determine which module is causing the issue. If you find a single module that is faulty you should contact the seller or the memory manufacturer and have them replace the memory as a SET. Memory comes matched for a reason as I made clear earlier and if you let them replace only one module rather than the entire set you are back to using unmatched memory which is an open door for problems with incompatible memory.

Be aware that you SHOULD run Memtest86 to test the memory at the default, non-XMP or custom profile settings BEFORE ever making any changes to the memory configuration so that you will know if the problem is a setting or is a physical problem with the memory.

If it passes, then install the other two memory modules and test again. If it fails, try bumping the DRAM voltage (Memory voltage) by .005-.020v (Whatever the lowest increment is the BIOS will allow you to increase the DRAM voltage by) in the BIOS, save settings and then re-test with memtest. Still fails, bump DRAM voltage again. Rinse and repeat. You can go all the way to 1.35v on the memory voltage (But don't just jump there from the beginning) if necessary to get all four sticks to pass. If by the time you get to 1.35v you still can't pass, then there is a problem with the memory itself in some way whether that's due to a problem with one stick or the fact that you have mixed memory that doesn't want to play nice together.

DarkBreeze
update on this issue
I already ran memtest on all memory and it passed.
I have re installed windows today (format and re-instal), as I only installed over the last version (from previous build) and am running real bench, and it is currently running ok, apart from the fact that LuxMark-64.exe has "stopped working" but real bench is still running.
is this normal?
I will re test memory tomorrow as I have set RealBench 2.43 to run for 4 hours so will let it finish (if it does)

Titan

You are running the "stress test" and not the benchmark, right? And you are choosing half of your full installed amount of memory on the settings for Realbench stress test, yes? Be sure not to do anything else, sorry, while running the stress test. Not only is it so resource intensive that trying to use the system normally becomes impossible, I've actually seen Realbench error out due to trying to do other things while running it due to memory allocation. Best to simply let it run.

Are you running it for the stock configuration or for your overclock? Because if you are running it for the stock configuration then one hour should be sufficient to say it's ok now. For an overclocked configuration, you want to run it for 8 hours. Not 2, or 4, or 6. Eight hours. I've seen instabilities on systems that passed 6 hours test runs when using other utilities to verify, but I've never seen an overclocked system fail to pass any other stability test after completing an 8 hour run of Realbench. Keep in mind that thermal compliance and stability are two entirely different things, and passing one doesn't mean the other is ok. Test them separately.

I was running stress test, but the third window (LuxMark) opened. I checked elsewhere and if I uncheck the GPU box in this window it runs ok.
I am testing my totally stock build (but with latest bios version) and it managed to complete a one hour test with half my memory configured.
I get it about thermal compliance, 15 mins of Small FTT prime 95 version 26.6, then a 1 hour RealBench test, then increase the speed and re test again.

I still have some software to instal (new Windows build like I said), but as I passed 1 hour RealBench with stock settings (not even XMP) would you agree that I am good to start my overclocking process?

Titan

Yes. I would agree. Take it slow and use the incremental process. It will pay off in a more stable and reliable overclock in the end.

Please note that at this point your memory should NOT be configured for XMP profile yet. Do that AFTER you are done configuring and testing your CPU overclock so that you will know that any errors or problems are not due to the memory configuration. Then after you are happy with the CPU configuration, THEN enable the XMP profile and then RE-TEST the memory configuration with Memtest86. That is important, and I outline WHY that is important in my overclocking guide and my memory guide.

Thank you again for your help, I really appreciate it.
I already have your two guides bookmarked and will be working through the CPU overclock as you advice in the guide, it will take me a while but I will get there, I will update you when I have completed both my CPU and Memory overclock.

Titan

No, neither is overclocking the memory beyond whatever the XMP profile specifications are. And for that, you don't need a memory cooler. The heatsinks on the memory do a fine job. I've never see any memory with even a mild overclock PAST the XMP profile, so like, going to 3200mhz with 3000mhz sticks, raise the temperature enough on the memory to need it. For major memory overclocking past their XMP specifications, then yeah, you might want it.

The bigger issue with overclocking memory is that it WILL increase temperatures on the CPU. Soooooo, when enable the XMP profile on the memory you will need to once again go back and test for thermal compliance on the CPU running Prime. The memory controller is IN the CPU for most modern, maybe ALL modern architectures. I know since Haswell at least, it is for Intel and it is for Ryzen as well. I can't remember if the FX series MC was in the CPU or on the motherboard. I'd have to revisit that. Been a while. Regardless, doesn't apply to you anyhow. So it can raise temps, and overclocking it, which I don't consider as an actual overclock when using the XMP profile even though it's usually listed as an OC on the motherboard specs, but actual overclocking will definitely and significantly raise those temps.

Titan

HI There,
Can I ask you a quick question on my overclock stability testing please?
I am running Real bench, and when I select Stress Test, select half my ram (16GB as I have 32GB in my machine), and when I click test, I get a third window pop up (LuxMark v2.1[RealBench Edition]), and in the Hardware Devices pane I am UNCHECKING the box nest to my Graphics card, I assume this is right because if I don't the LuxMark element crashes (not responding), is this correct?
I only ask as so far using your incremental guide I have overclocked successfully to 4.8GHz at stock voltage of 1.2v and it is passing thermal compliance and stability testing described above (graphics card unchecked in hardware devices pane)
I appreciate your help
Thanks
Nick

Titan

Let me retract that last statement. Been a while since ran Realbench on MY system. You do need to leave the LuxMark window open. It is an all inclusive stress test, but it seems a lot of Nvidia cards trigger errors. I would first try doing a clean install of your graphics drivers, and then retest, before trying to go any further.

Here are the full instructions on running the Display driver uninstaller and CLEAN installing new drivers.

Also, if in doubt with Realbench results, you can, and probably SHOULD, also run the following tests before moving beyond where you are now on your OC. Personally, I don't think anything beyond 4.8Ghz should be used on a full time, daily driver CPU UNLESS that CPU has a stock single core boost speed that is higher than that. Sure, some people do, but some people also don't care if their CPU lasts three years, or five, because they upgrade every cycle. If that's not you, I'd stick to what you already have PLUS run the following tests to ensure it is actually fully stable, especially if you DO plan to push it further.

Final testing with Prime95

It is highly advisable that you do a final test when overclocking your memory (But can also be used as a CPU overclocking test for further verification) using Prime95 version 26.6 (And ONLY version 26.6 except as noted below) choosing the Custom test. You can also use the Blend mode option but after a fair amount of personal testing, asking questions from some long time members with engineering level degrees that have forgotten more about memory architectures than you or I will ever know, and gathering opinions from a wide array of memory enthusiasts around the web, I'm pretty confident that the custom option is a lot more likely to find errors with the memory configuration, and faster, if there are any to be found.

Please note as this is rather important, if you prefer, or have problems running version 26.6 because you have a newer platform that doesn't want to play nice with version 26.6, you can use the latest version of Prime95 with the Custom test selected but you will need to make the following change.

If you wish to use a newer version than 26.6 make the following edit to the "local.txt" file located in the Prime95 folder.

Find the line value that specifies CpuSupportsAVX=1, and change it to CpuSupportsAVX=0

Then click File-->Save, and then close the document.

Now open Prime95.

Click on "Custom". Input a value of 512k in the minimum FFT size field. Leave the maximum FFT size field at 4096k. In the "Memory to use" field you should take a look at your current memory allocation in either HWinfo or system resource monitor. Whatever "free" memory is available, input approximately 75% of that amount. So if you currently have 16GB of installed memory, and approximately 3GB are in use or reserved leaving somewhere in the neighborhood of 13GB free, then enter something close to 75% of that amount.

So if you have 13GB free, or something reasonably close to that, then 75% of THAT would be 9.75GB, which, when multiplies times 1024 will roughly equal about 9984MB. You can average things out by simply selecting the closest multiple of 1024 to that amount just to keep it simple, so we'll say 10 x 1024= 10240mb and enter that amount in the field for "Memory to use (MB)". We are still well within the 13GB of unused memory BUT we have left enough memory unused so that if Windows decides to load some other process or background program, or an already loaded one suddenly needs more, we won't run into a situation where the system errors out due to lack of memory because we've dedicated it all to testing.

I've experienced false errors and system freezes during this test from over allocating memory, so stick to the method above and you should be ok.

Moving right along, do not change the time to run each FFT size.Leave that set to 15 minutes.

Click run and run the Custom test for 8 hours. If it passed Memtest86 and it passes 8 hours of the Custom test, the memory is 100% stable, or as close to it as you are ever likely to get but a lot of experts in the area of memory configuration suggest that running the extended Windows memory diagnostic test is also a pretty good idea too.

If you get errors, (and you will want to run HWinfo alongside Prime95 so you can periodically monitor each thread as Prime will not stop running just because one worker drops out, so you need to watch HWinfo to see if there are any threads not showing 100% usage which means one of the workers errored and was dropped) then you need to either change the timings, change the DRAM voltage or change the DRAM termination voltage, which should be approximately half of the full DRAM voltage.

There are also other bios settings that can affect the memory configuration AND stability, such as the VCCIO and system agent voltages, so if you have problems with stability at higher clock speeds you might want to look at increasing those slightly. Usually, for Intel at least, something in the neighborhood of 1.1v on both those is pretty safe. There are a substantial number of guides out there covering those two settings, but most of them are found within CPU overclocking guides so look there in guides relevant to your platform.

Let me retract that last statement. Been a while since ran Realbench on MY system. You do need to leave the LuxMark window open. It is an all inclusive stress test, but it seems a lot of Nvidia cards trigger errors. I would first try doing a clean install of your graphics drivers, and then retest, before trying to go any further.

Here are the full instructions on running the Display driver uninstaller and CLEAN installing new drivers.

Also, if in doubt with Realbench results, you can, and probably SHOULD, also run the following tests before moving beyond where you are now on your OC. Personally, I don't think anything beyond 4.8Ghz should be used on a full time, daily driver CPU UNLESS that CPU has a stock single core boost speed that is higher than that. Sure, some people do, but some people also don't care if their CPU lasts three years, or five, because they upgrade every cycle. If that's not you, I'd stick to what you already have PLUS run the following tests to ensure it is actually fully stable, especially if you DO plan to push it further.

Final testing with Prime95

It is highly advisable that you do a final test when overclocking your memory (But can also be used as a CPU overclocking test for further verification) using Prime95 version 26.6 (And ONLY version 26.6 except as noted below) choosing the Custom test. You can also use the Blend mode option but after a fair amount of personal testing, asking questions from some long time members with engineering level degrees that have forgotten more about memory architectures than you or I will ever know, and gathering opinions from a wide array of memory enthusiasts around the web, I'm pretty confident that the custom option is a lot more likely to find errors with the memory configuration, and faster, if there are any to be found.

Please note as this is rather important, if you prefer, or have problems running version 26.6 because you have a newer platform that doesn't want to play nice with version 26.6, you can use the latest version of Prime95 with the Custom test selected but you will need to make the following change.

If you wish to use a newer version than 26.6 make the following edit to the "local.txt" file located in the Prime95 folder.

Find the line value that specifies CpuSupportsAVX=1, and change it to CpuSupportsAVX=0

Then click File-->Save, and then close the document.

Now open Prime95.

Click on "Custom". Input a value of 512k in the minimum FFT size field. Leave the maximum FFT size field at 4096k. In the "Memory to use" field you should take a look at your current memory allocation in either HWinfo or system resource monitor. Whatever "free" memory is available, input approximately 75% of that amount. So if you currently have 16GB of installed memory, and approximately 3GB are in use or reserved leaving somewhere in the neighborhood of 13GB free, then enter something close to 75% of that amount.

So if you have 13GB free, or something reasonably close to that, then 75% of THAT would be 9.75GB, which, when multiplies times 1024 will roughly equal about 9984MB. You can average things out by simply selecting the closest multiple of 1024 to that amount just to keep it simple, so we'll say 10 x 1024= 10240mb and enter that amount in the field for "Memory to use (MB)". We are still well within the 13GB of unused memory BUT we have left enough memory unused so that if Windows decides to load some other process or background program, or an already loaded one suddenly needs more, we won't run into a situation where the system errors out due to lack of memory because we've dedicated it all to testing.

I've experienced false errors and system freezes during this test from over allocating memory, so stick to the method above and you should be ok.

Moving right along, do not change the time to run each FFT size.Leave that set to 15 minutes.

Click run and run the Custom test for 8 hours. If it passed Memtest86 and it passes 8 hours of the Custom test, the memory is 100% stable, or as close to it as you are ever likely to get but a lot of experts in the area of memory configuration suggest that running the extended Windows memory diagnostic test is also a pretty good idea too.

If you get errors, (and you will want to run HWinfo alongside Prime95 so you can periodically monitor each thread as Prime will not stop running just because one worker drops out, so you need to watch HWinfo to see if there are any threads not showing 100% usage which means one of the workers errored and was dropped) then you need to either change the timings, change the DRAM voltage or change the DRAM termination voltage, which should be approximately half of the full DRAM voltage.

There are also other bios settings that can affect the memory configuration AND stability, such as the VCCIO and system agent voltages, so if you have problems with stability at higher clock speeds you might want to look at increasing those slightly. Usually, for Intel at least, something in the neighborhood of 1.1v on both those is pretty safe. There are a substantial number of guides out there covering those two settings, but most of them are found within CPU overclocking guides so look there in guides relevant to your platform.

I tried uninstalling and re installing my graphics drivers, and I got the same issue, the LuxMark window stops working, but the RealBench continues running regardless with CPU at 100%.
As this is a fresh windows install (2 weeks old and no shite loaded on it yet!) I don't think that re installing windows will get us anywhere.
so it its current state, what is RealBench actually telling me, is it telling me anything about my overclock?
are there other reliable methods of proving or disproving stability of an overclock?
any help is apprecuted
Cheers

Titan

Realbench is accurate, even without the LuxMark running. I listed an alternate stability test above on my last post.

You can also run a variety of other, less definitive but certainly still somewhat demonstrative stability tests as well.

Prime95 version 26.6 Small FFT for 24 hours is a decent indicator.
The Prime95 custom test I listed above is a very good indicator of both CPU and memory stability, but is more focused on memory than CPU.
Intel burn test has some value.
Heavy load has some value.
The H.264 stress testing variants have value.

If you open the stress testing section at the following link, most of the methods offered there have value, although I don't agree with EVERYTHING they believe or offer as fact. Most of it still has value though.

Realbench is accurate, even without the LuxMark running. I listed an alternate stability test above on my last post.

You can also run a variety of other, less definitive but certainly still somewhat demonstrative stability tests as well.

Prime95 version 26.6 Small FFT for 24 hours is a decent indicator.
The Prime95 custom test I listed above is a very good indicator of both CPU and memory stability, but is more focused on memory than CPU.
Intel burn test has some value.
Heavy load has some value.
The H.264 stress testing variants have value.

If you open the stress testing section at the following link, most of the methods offered there have value, although I don't agree with EVERYTHING they believe or offer as fact. Most of it still has value though.

Many thanks, I think I will continue with RealBench without luxmark and use it to assess stability up to my target of 5GHz, then I will run through the other tests you mention to confirm this. I will then switch between the stable 5GHz and the Stable 4.6GHz I have tested depending on what I am using my PC for.